Goodnight, Moon

Luna joins several luminaries, but its disappearing act is the best

By J. Alex Knoll

The moon waxes through the weekend, until Tuesday’s full moon, known as the Grass Moon, the Egg Moon and the Pink Moon. This is also the first full moon since vernal equinox, the Paschal Moon, marking the start of Passover and setting the date for Easter the following Sunday.
Thursday the bright gibbous moon hovers below the first-magnitude star Regulus, heart of Leo the lion. Stretching up from the star like an inverted question mark is the Sickle of Leo, which marks the head of the celestial lion. Located along the ecliptic — the pathway through the heavens of the sun, moon and planets — Regulus is joined every month by the moon, which is never more than five degrees away.
The following nights the moon marches eastward against the backdrop of stars, leaving Leo and approaching Virgo. By Saturday it is in a barren patch of sky, midway between Regulus and equally bright Spica to the east. Don’t confuse Spica’s blue-white glow with that of ruddy Mars a few degrees away.
By Sunday, the moon forms an uneven triangle with Mars and Spica, its shape shifting as the three objects pivot to the west. Monday the near-full moon is within five degrees of Mars — and about half that distance from Spica. The three are so close that they will all fit within the field of view of binoculars or telescope. Come Wednesday, the moon comes within a few degree os Saturn amid the faint stars of Libra. Tuesday, the full moon rises as the sun sets and sets the next morning at sunrise. But in between, a little before 1am, the moon slowly inches behind earth’s full shadow, or umbra, in a total lunar eclipse. The eclipsed moon never actually disappears, but it does darken considerably, sometimes taking on a coppery or even blood-red hue as if illuminated from within. While the hours are for night owls, we’re in prime position to see this along Chesapeake Bay (as is most of North and South America as well as Australia). Unlike an eclipse of the sun, you can stare at this all you want with no worries.
Beginning around 1am, the moon crosses into earth’s outer, or penumbral, shadow. The change is slow and subtle, with the moon’s left, or northwest, edge starting to darken ever so slightly. But by 2am, as the moon slips behind the umbral shadow, the darkness spreads and deepens. The total phase begins at 3:07am, and at 3:46 the moon, earth and sun will be almost perfectly aligned, with the moon appearing as an eerie shadow of its usual self. Totality ends at 4:25am, and by 5:33 the moon will have crept from the umbral shadow. As daybreak draws near, the moon escapes earth’s shadow, only to set in the west.